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Family environment and the malleability of cognitive ability: A Swedish national home-reared and adopted-away cosibling control study.

Kendler, Ken LU ; Turkheimer, Eric; Ohlsson, Henrik LU ; Sundquist, Jan LU and Sundquist, Kristina LU (2015) In Proceedings of the National Academy of Sciences 112(15). p.4612-4617
Abstract
Cognitive ability strongly aggregates in families, and prior twin and adoption studies have suggested that this is the result of both genetic and environmental factors. In this study, we used a powerful design-home-reared and adopted-away cosibling controls-to investigate the role of the rearing environment in cognitive ability. We identified, from a complete national Swedish sample of male-male siblings, 436 full-sibships in which at least one member was reared by one or more biological parents and the other by adoptive parents. IQ was measured at age 18-20 as part of the Swedish military service conscription examination. Parental educational level was rated on a 5-point scale. Controlling for clustering of offspring within biological... (More)
Cognitive ability strongly aggregates in families, and prior twin and adoption studies have suggested that this is the result of both genetic and environmental factors. In this study, we used a powerful design-home-reared and adopted-away cosibling controls-to investigate the role of the rearing environment in cognitive ability. We identified, from a complete national Swedish sample of male-male siblings, 436 full-sibships in which at least one member was reared by one or more biological parents and the other by adoptive parents. IQ was measured at age 18-20 as part of the Swedish military service conscription examination. Parental educational level was rated on a 5-point scale. Controlling for clustering of offspring within biological families, the adopted siblings had an IQ 4.41 (SE = 0.75) points higher than their nonadopted siblings. Each additional unit of rearing parental education was associated with 1.71 (SE = 0.44) units of IQ. We replicated these results in 2,341 male-male half-sibships, in which, controlling for clustering within families, adoption was associated with a gain of IQ of 3.18 (SE = 0.34) points. Each additional unit of rearing parental education was associated with 1.94 (SE = 0.18) IQ units. Using full- and half-sibling sets matched for genetic background, we found replicated evidence that (i) rearing environment affects IQ measured in late adolescence, and (ii) a portion of the IQ of adopted siblings could be explained by the educational level of their adoptive parents. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
in
Proceedings of the National Academy of Sciences
volume
112
issue
15
pages
4612 - 4617
publisher
National Acad Sciences
external identifiers
  • pmid:25831538
  • wos:000352856800042
  • scopus:84928152357
ISSN
1091-6490
DOI
10.1073/pnas.1417106112
language
English
LU publication?
yes
id
be8070d3-0743-4a19-b3ff-f6bc49ded93b (old id 5360312)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/25831538?dopt=Abstract
date added to LUP
2015-05-07 18:37:19
date last changed
2017-11-05 03:08:43
@article{be8070d3-0743-4a19-b3ff-f6bc49ded93b,
  abstract     = {Cognitive ability strongly aggregates in families, and prior twin and adoption studies have suggested that this is the result of both genetic and environmental factors. In this study, we used a powerful design-home-reared and adopted-away cosibling controls-to investigate the role of the rearing environment in cognitive ability. We identified, from a complete national Swedish sample of male-male siblings, 436 full-sibships in which at least one member was reared by one or more biological parents and the other by adoptive parents. IQ was measured at age 18-20 as part of the Swedish military service conscription examination. Parental educational level was rated on a 5-point scale. Controlling for clustering of offspring within biological families, the adopted siblings had an IQ 4.41 (SE = 0.75) points higher than their nonadopted siblings. Each additional unit of rearing parental education was associated with 1.71 (SE = 0.44) units of IQ. We replicated these results in 2,341 male-male half-sibships, in which, controlling for clustering within families, adoption was associated with a gain of IQ of 3.18 (SE = 0.34) points. Each additional unit of rearing parental education was associated with 1.94 (SE = 0.18) IQ units. Using full- and half-sibling sets matched for genetic background, we found replicated evidence that (i) rearing environment affects IQ measured in late adolescence, and (ii) a portion of the IQ of adopted siblings could be explained by the educational level of their adoptive parents.},
  author       = {Kendler, Ken and Turkheimer, Eric and Ohlsson, Henrik and Sundquist, Jan and Sundquist, Kristina},
  issn         = {1091-6490},
  language     = {eng},
  number       = {15},
  pages        = {4612--4617},
  publisher    = {National Acad Sciences},
  series       = {Proceedings of the National Academy of Sciences},
  title        = {Family environment and the malleability of cognitive ability: A Swedish national home-reared and adopted-away cosibling control study.},
  url          = {http://dx.doi.org/10.1073/pnas.1417106112},
  volume       = {112},
  year         = {2015},
}